image labelling for background

I want to label images in order to use it in semantic segmentation

However, i want to label only specific area,

so if i only mark specific areas in whole image dataset

the areas which are not mark are automatically assumed as background?

Or do i have to mark it manually mark it as background as well?

Answer 1

[Image Analyst]

It depends on what you want to do. If you only process the things you have labeled, then you don't need to worry about the background being labeled since even if it were, you'd not process it. If you want to process it, then you need to label it.

[fatihveysel nurcin]

what do you mean by process, i only want to segment 1 object in the image, for that do i need to label background for all images ?

[Bashar Saad]

Sir, did you volve this problem or yet?

i need the solution of it

[Gurpreet Singh Tuteja]

Same problem I also want to segment one object, have you got the solution?

Please help

[Image Analyst]

You do not need to label the background (i.e. with bwconncomp or bwlabel). All you need to do is to segment out the foreground and process it (like find the area, brightness or whatever you want to do.) I go over all this in my Image Segmentation Tutorial

[OJ27]

any solution to this? is there an automatic way to label the undefined pixels as background? I want to use a cnn to do semantic segmentation of a specific object. The examples MATLAB offers come with datasets that two classes and no undefined pixels.

Answer 2

[OJ27]

So I solved this by only labeling the desired areas in my images with the class cat and the background was left without a label.

pxDir = fullfile('...'); % insert your directory
imds = imageDatastore('...'); % insert your directory
classNames = ["cat"];
pixelLabelID = [1];
pxds = pixelLabelDatastore(pxDir,classNames,pixelLabelID);
C = readimage(pxds,1);
undefinedPixels = isundefined(C);

If you look at C, the entries are either '<undefined>' or 'cat'. Also if you look at undefinedPixels you'll see how many of the pixels have this label and you can even plot it. So I replaced these two lines

classNames = ["cat","background"];
pixelLabelID = [1,0];

and now C shows either 'background' or 'cat'. If you run the

undefinedPixels = isundefined(C); 

again, you'll find sum(sum(undefinedPixels)) is zero.